Conventionally, as a nonvolatile memory device having a large capacity, a NAND type flash memory has been frequently used. However, it is going to be close to a physical limit in connection with a refining of an element, and there have been recently developed new memories such as a ferroelectric memory, a magnetic resistance memory, a phase change memory, a resistance change type memory and the like. Among them, an ion memory is remarked as one of the resistance variable memory, the ion memory being one kind of a conductive bridging random access memory (CBRAM).
A memory cell of the ion memory generally has a rewritable memory layer (a rewritable layer), a metal ion supply layer for introducing a metal atomic element to the rewritable layer, and a facing electrode layer which is arranged in a reverse side to the metal ion supply layer.
In the case that the ion memory is used as a cell array, a word line and a bit line are arranged above and below the memory cell, for applying an electric potential or an electric current from an external portion so as to carry out a writing, a deleting and a reading. A so-called cross point type memory is considered to be the highest in a degree of integration, the cross point type memory has structures that the bit line and the word line are arranged so as to intersect, and the bit line and the word line are alternately stacked. In the case that the memory cell is used as the cell array, it is necessary to have a rectifying function for the cell array. For this purpose, in addition to a connection in series of a rectifying element to each of the memory cells, there has been also made a study of provision of the rectifying function in the facing electrode.
For the ion memory mentioned above, there is demand that the memory cell has a reliable structure in which a pattern collapse and a pattern strain are hard to be generated in the course of a manufacturing process in connection with a refining of an element.